Pole-shoe.



No. 897,824. PATENTED SEPT. 1, 1908.

w. R. EVERETT a; E. J. NEWTON.

POLE SHOE. APPLICATION FILED AUG.1'7, 1904.

WIT E5555: 1 NTORS Mumaw ms Mmms Peru's cm, u'Asmimran. o. c.

UNITED STATES PATENT OFFICE.

WILLIAM It. EVERETT AND EDWIN .T. NEWTON, OF CHICAGO, ILLINOIS.

POLE-SHOE Specification of Letters Patent.

Patented Sept. 1, 1908..

Application filed August 17, 1904. Serial No. 221,021.

To all whom it may concern:

Be it known that we, WVILLIAM R. EVER- ETT and EDWIN J. NEWTON, residingat Chicago, in the county of Cook and State of Illinois, have inventedcertain new and useful Pole-Shoes for the Transmission of Magnetic Linesof Force Through Economical Paths, of which the following is aspecification.

Our invention is utilized on that class of machinery called magneticengines or motors. The construction of magnetic engines Was practicallyabandoned at about the time of the inception of the present type ofelectric motor. This abandonment was due largely to the inability toconstruct a magnetic engine with a commercial degree of efficiency owingto the loss occasioned by the separation of the poles as Well as thenecessity of leaving a large air gap and to prevent the electro-magnetsdrawing together, which air gap offering as it does a high reluctance tothe transmission of the lines of magnetic force, destroyed theefficiency of the engines as well as the fact that when the air gap wasmaterially reduced the tension put upon the machine due to the tendencyof the magnetic circuits to shorten themselves, caused a constant strainupon the machine and a tendency to distort it.

Magnetic engines or motors are extremely desirable forms for producingmotion from an electric current, owing to the fact that it becomespossible with their use to obtain a high initial torque without anypossibility of burning out the engine or motor with the intensity of thecurrent.

The object of our invention is to produce a shoe the use of which willavoid the above difliculties, and not only provide a method ofeliminating the air gap due to the separation of the poles, topractically nothing, but to provide means whereby the current isdeflected and caused to pass laterally through 0pposite sides andcomplete the circuit through a medium of low reluctance.

Our method of attaining this object may be more readily understood byhaving reference to the accompanying drawings, which are a part of thisspecification and are hereunto annexed, in which Figure 1 is a sideelevation showing our improved form of pole shoe, Fig. 2 isa top or planview of the same, Fig. 3 is a detail view showing the manner ofdirecting the line of force, Fig. 4 is a similar view of a modified formof construction.

Similar letters refer to similar throughout the entire description.

In the drawings, the shoes are shown mounted upon the cores (0 and b oftwo opposing electro-magnets. The shoes a are formed with two projectingarms a and a which are offset on opposite sides. Shoulders a and a areformed on these arms. The shoes are held in place by means of screws cor any other convenient method of fastening. A shoulder a is formed onthe lower side of the shoe and recessed into the core a, thuseliminating the shearing strain from the screw a The opposite shoecorresponds inconstruction to the shoe c with the exception that-it isprovided with recesses b and 6 They are secured in place by means ofscrews 1)" or any other convenient method; the shoulder 12 beingrecessed in corresponding manner into the core I). Strips ofnon-magnetic material 0 c and c are placed upon the faces of the shoe bSimilar non-magnetic strips are placed at the top of the recesses b and5 The result of this construction is at once apparent. The nonmagneticstrips serve to retard and deflect the lines of magnetic force and sincethey seek the paths of least resistance it follows that they passthrough the sides (LS and a of the shoulders and recesses as indicatedby the arrows in the drawings, and since the tendency is no greater forthem to How through the sides a than the sides a, it will be seen thatthe shoes are balanced and it becomes possible to reduce the air gapbetween the sides to the smallest fraction of an inch consistent withmotion without any danger of them drawing together and by this pressureincreasing the friction to such an extent as to practically makemovement impossible. This in connection with the doing t way of the lossdue to the separation of the poles which we accomplish by means of theoverlapping of the extended arms a and (L3 raises the efiiciency to amaximum.

Many modifications one of which is shown in Fig. 4 in the constructionof these shoes, will suggest themselves to persons skilled in the art,which will not deviate from the spirit of our invention, which is toprovide means parts to deflect the lines of magnetic force causing themto pass laterally in relation to the shoes in opposite directions, andto provide means, i. 6., overlapping shoes, for reducing the lossoccasioned by the separation of the poles, and We do not Wish to belimited to the precise construction shown in the drawings.

Having described our invention, What We regard as new and desire tosecure by Letters Patent is 1. Pole shoes for magnetic engines ormotors, said shoes being formed With extended arms, said arms beingoffset on opposite sides and overlapping the arms of the next shoe, saidshoes having circumferential grooves formed therein, corresponding poleshoes having shoulders thereon, said shoulders fitting to and coincidingwith the said circumferential grooves, for the purpose set forthsubstantially as described.

2. Pole shoes for magnetic engines or motors, said shoes being formedWith extended arms, said arms being oflset on opposite sides andoverlapping the arms of the next shoe, said shoes having circumferentialgrooves formed therein, corresponding pole shoes having shouldersthereon, said shoulders fitting to and coinciding With the saidcircumferential grooves, strips of non-magnetic material mounted in saidgrooves, for the purpose set forth substantially as described.

WVILLIAM R. EVERETT. EDlVIN J. NElVTON Vitnesses:

W. H. STIOKEL, N. MoKUsIoK.

